Annals of Neurology

BackgroundMutations in the E3 ubiquitin ligase Parkin (encoded by PRKN) are the most frequently known cause of recessively inherited Parkinsons disease. In addition to the loss of dopaminergic neurons, microglial activation is another pathological feature observed in Parkinsons disease. While postmortem brain samples show the end stage of the disease, neurons and glia derived from patients induced pluripotent stem cells (iPSCs) provide a model for detecting early pre-degenerative disease trajectories. However, mixed cell populations often confound these cultures, leading to heterogeneous disease phenotypes. MethodsHere, we tease apart the cell type-specific phenotypes underlying Parkin-linked Parkinsons disease by performing single-nucleus RNA sequencing in iPSC-derived co-cultures of dopaminergic neurons and microglia from PRKN mutation carriers and healthy controls. We validated our transcriptomic key findings through inflammatory cytokine profiling and live-cell calcium imaging. ResultsSingle-nucleus RNA sequencing identified seven major cell types composed of neuronal, glial, and precursor cells, with dopaminergic neurons accounting for the largest cell population. Pathway analysis revealed cell type-specific dysregulated biological processes in Parkin-deficient cells, including gene expression differences in dopaminergic neurons that control mitophagy and dopamine homeostasis, whereas microglia showed changes in calcium homeostasis and inflammatory signaling. Functional analysis verified elevated secretion of monocyte chemotactic protein 1 in PRKN-mutant co-cultures compared with controls, linking Parkin deficiency to increased microglial chemotactic signaling. Furthermore, lower intracellular calcium levels and diminished calcium release following treatment confirmed impaired calcium homeostasis in PRKN-mutant microglia. ConclusionsProfiling at the single-cell level resolved distinct cell subpopulations, enabling us to identify cell type-specific pathway disturbances underlying Parkin deficiency. This unique dataset provides a basis for understanding the impairment of individual cell types and the impact of cellular crosstalk in Parkinsons disease pathology.

BackgroundPostoperative delirium (POD) is a frequent and severe neurocognitive complication following cardiac surgery, associated with poor long-term outcomes. The underlying mechanisms are unclear, and objective biomarkers are urgently needed. MethodsWe used pre- and post-operative plasma samples from 59 patients undergoing cardiac surgery in three separate studies with rigorous delirium assessment using the Confusion Assessment Method in a case-control design. Small extracellular vesicles (sEVs) were isolated from plasma, and their miRNA cargo was profiled using RNA sequencing. Target miRNAs were validated by qRT-PCR, and digital PCR (dPCR). The functional impact of the lead candidate miRNA was investigated in vitro by assessing tau phosphorylation and cell viability in HT22 neuronal cell line. ResultsThere were no differences in sEV morphology or numbers between patients with and without POD. While three candidate miRNAs were initially validated by qRT-PCR, subsequent dPCR analysis confirmed that only the perioperative change in plasma sEV-cargo miR-330-3p expression was significantly greater in patients who developed POD (n = 20) compared with those who did not (n = 20) (5.22 copies/L plasma; 95% Confidence Interval (CI), 1.187 to 9.256; p = 0.0139). Receiver operating characteristic curve analysis for this change yielded an area under the curve of 0.745 (95% CI, 0.589 to 0.901). In vitro overexpression of miR-330-3p in a neuronal cell line significantly increased the phosphorylation of tau at Ser199 (p < 0.0001) and Ser396 (p < 0.001) and reduced cell viability (p < 0.001). ConclusionsOur findings suggest that sEV-bound miR-330-3p increases in patients with POD after cardiac surgery. In vitro results suggest a potential pathogenic role for miR-330-3p, linking a systemic signal to tau-related neuronal injury. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABSO_LIThis study identifies a specific perioperative increase in small extracellular vesicle (sEV)-cargo miR-330-3p in patients with postoperative delirium (POD) following cardiac surgery. C_LIO_LIWe provide the first evidence that miR-330-3p directly induces tau hyperphosphorylation and reduces neuronal viability in vitro, establishing a potential mechanistic link between systemic sEV signaling and neurodegeneration. C_LI What Are the Clinical Implications?O_LIThe measurement of perioperative change in miR-330-3p could serve as an objective biological marker to assist in the early identification and risk stratification of patients at high risk for POD. C_LIO_LIThe identified miR-330-3p/tau pathway represents a potential new therapeutic target; future interventions aimed at inhibiting this specific miRNA might help prevent or mitigate POD-related neuronal injury. C_LIO_LIThese findings emphasize the importance of monitoring dynamic sEV-cargo changes to better understand and manage perioperative neurocognitive disorders. C_LI

Objective: Predicting specific cognitive, psychiatric, and health-related sequelae in patients after acute traumatic brain injury (TBI) remains an important but challenging clinical problem. Acute phase computed tomography (CT) scans acquired show hemorrhagic contusions, a common type of traumatic pathology. However, whether CT-measured contusions predict long-term sequelae is uncertain. Methods: We established a Screening Cohort of patients with acute TBI who received care at a single TBI Model Systems (TBIMS) inpatient rehabilitation facility. Regions of hemorrhagic contusion and edema were labeled on acute brain CT scans using the fully-automated Brain Lesion Analysis and Segmentation Tool (BLAST-CT). We screened 198 outcome variables at 1-year post-injury for association with acute hemorrhagic contusion volume using the Harrell's Concordance index (C-index), controlling for multiple comparisons using 5,000 outcome permutations. Finally, we tested whether the significant associations in the TBIMS database replicated in acute (Transforming Research and Clinical Knowledge in TBI [TRACK-TBI]) and chronic (Vietnam Head Injury Study [VHIS]) external validation cohorts. Results: The TBIMS Screening Cohort included 345 participants (mean {+/-} SD age: 55.7 {+/-} 21.5 years) with median [IQR] contusion volume 2.3 cc [0.1, 14.6]. Among 198 candidate outcome variables, only delayed seizures were significantly associated with acute hemorrhagic contusion volume (C-index = 0.81; PFWE = 0.007). Contusion volume was not significantly associated with commonly-used measures of global functioning like the Glasgow Outcome Scale Extended, (C-index = 0.55; PFWE = 1). Within the screening cohort, 30 ccs was the optimal volume threshold for discriminating patients with versus without delayed seizures (OR 12.6, 95% CI: [4.6, 34.3]). Contusions larger than 30 cc remained significantly associated with delayed seizures in two external cohorts: (TRACK-TBI OR 4.1 [1.5, 11.2]; VHIS OR 3.2 [1.7, 6.2]). Interpretation: Across three cohorts of patients with TBI, CT-derived contusion volume is robustly associated with the development of delayed seizures, in contrast to commonly-used outcomes measuring global functioning. A 30-cc volume threshold can be used to improve epilepsy prediction models and enrich populations for clinical trials.

BackgroundNeuroinflammation is a common hallmark of primary tauopathies, and is associated with worse clinical outcomes over time. However, accurate prognosis in these disorders remains challenging, and current fluid biomarkers provide limited insight into the contribution of peripheral immune cells to PSP/CBS pathogenesis. Our study aims to characterise blood-based immune cell profiles in patients with progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), and test their associations with neurodegeneration and clinical outcomes. MethodsPeripheral blood immune cells from fresh whole blood were characterized with high-dimensional mass cytometry (29 markers) in n=60 people with PSP/CBS and n=21 age- and sex-matched controls. Cell type abundance was defined as the ratio of counts for each gated population divided by total live cells. Hierarchical clustering of cell types and principal component analysis were used to derive data-driven immune clusters. Correlation network analysis and diffusion-based network propagation integrated cell counts with plasma inflammation markers to prioritise mediators of intercellular signalling. Associations between immunological markers, plasma concentrations of neurofilament light chain (NfL), cognition, and survival were assessed using regression and Cox proportional hazards models. ResultsPatients with PSP/CBS showed a global increase in covariance among immune cell populations, indicating heightened coordination within the peripheral immune network. A monocyte-driven cluster (Cluster 1) showed higher scores in PSP/CBS, reflecting impaired phenotypic transition from classical to nonclassical monocytes, and was associated with higher NfL levels, poorer cognitive performance, and worse prognosis. In contrast, a Treg-driven cluster (Cluster 2) showed lower scores in PSP/CBS, and was associated with better cognition and longer survival. Integrated multimodal networks identified a small set of immune-regulatory molecules and cytokines mediating crosstalk between Treg/Th17-like cells and monocytic populations, supporting a dysregulated Treg-monocyte axis in PSP/CBS. ConclusionsWe identified peripheral blood-based immunophenotypic profiles of individuals with PSP/CBS that are associated with neurodegeneration, cognitive decline, and survival. Dysregulated monocyte maturation and reduced Treg-related immune configurations are enriched in patients with worse outcomes, suggesting that specific peripheral immune cell subsets may serve as fluid biomarkers and potential immunotherapy targets in primary tauopathies.

Objective. Continuous, unsupervised monitoring of cognitive brain responses has long been constrained by the demands of laboratory EEG. Whether the P300 event-related potential, an established marker of attention and cognitive processing, can be elicited as an incidental byproduct of genuine gameplay, recorded with a minimal wearable EEG system under unsupervised home conditions, has not been established. Approach. Ten healthy adults played a gamified visual oddball task in which infrequent target stimuli (green gates) were embedded among frequent non-targets (red gates) within a continuous third-person running game. EEG was recorded with a four-channel dry-electrode headband (EEG channels: O1, O2, T3, T4; forehead reference; 250Hz) with self-mounted electrodes in a home setting, without experimenter supervision. Group-level effects were assessed with cluster-based permutation tests and peak-amplitude tests. Single-trial classification used linear discriminant analysis (LDA) with four features per channel (16 total). Additional analyses included a within-subject comparison with a classical visual oddball paradigm using identical hardware, pilot data from a patient with relapsing-remitting multiple sclerosis, within-subject stability across 48 sessions, and pilot recordings with a headphone form factor. Main results. A robust P300-like difference wave emerged on all four channels at the group level (cluster-based permutation tests, p < 0.05), with individual-level detection in 8 of 10 participants (exact binomial p < 0.001). Single-trial LDA yielded a median cross-validated AUC of 0.730 (95% CI 0.672-0.820), with 9 of 10 participants exceeding chance. In a within-subject comparison, waveform morphology was closely preserved relative to a classical laboratory oddball, and classification performance was markedly higher in the game condition (AUC 0.820 versus 0.555). A patient with relapsing-remitting multiple sclerosis produced a clear P300 (AUC 0.853) with latencies within the healthy range. Within-session split-half reliability was high (r > 0.70 on three of four channels), though between-session reliability was near zero across 48 sessions in one participant, with a declining classification trend over time. Pilot recordings with a headphone form factor also yielded a P300-like deflection. Significance. These results demonstrate that the P300 can be elicited as a gameplay-integrated neural readout during genuine gameplay with a wearable, dry-electrode EEG system under unsupervised conditions. Gamification does not compromise P300 elicitation; in the within-subject comparison, it enhanced single-trial discriminability. The findings indicate that gamified, home-based P300 monitoring is achievable with minimal hardware and provide preliminary evidence for applicability in clinical populations, most notably multiple sclerosis, where P300 has established biomarker value but where the logistical burden of laboratory assessment currently precludes longitudinal use.

BackgroundAcute necrotizing encephalopathy (ANE) is a rare and severe neurologic complication of viral infection in children, thought to result from a hyperacute cytokine storm causing blood-brain barrier disruption and central nervous system injury. Despite characteristic clinical and radiologic features, ANE remains poorly understood at the molecular level, with no validated biomarkers or targeted therapies. We aimed to determine whether genetic predisposition to ANE due to RANBP2 variants is associated with a distinct immunologic signature. MethodsWe conducted a prospective biological study of familial ANE (ANE1, NCT06731790). We included 23 heterozygous carriers of the RANBP2 c.1754C>T (p.Thr585Met) variant from 10 families, and 28 noncarriers (median age, 40 years [range, 4-72]). Soluble immune mediators, transcriptomic analyses, multiparameter flow cytometry, and cellular imaging were analysed in peripheral blood mononuclear cells (PBMCs) and monocytes. Baseline and resiquimod-stimulated immune responses were analysed within the same statistical model, with genetic status as the primary predictor. FindingsThe RANBP2 Thr585Met mutation was associated with a dysregulated inflammatory phenotype characterized by reduced basal mediator production and exaggerated TNF- responses following stimulation (estimated difference, +2,098 pg/mL; 95% CI, 1,121 to 3,076; P=0.0001). Transcriptomic and flow cytometry analyses showed broad reprogramming of myeloid cells with enrichment of CXCR3-high CD14-high subsets. Expansion of these populations was associated with increased long-term disease burden. The RANBP2 variant was the only independent factor associated this inflammatory phenotype. Interpretation: RANBP2-associated ANE is characterised by a distinct immunological signature that can inform disease stratification and support the development of targeted immunotherapeutic approaches.

Background and ObjectivesOlder adults with epilepsy have a 2- to 4-fold increased risk of dementia, including Alzheimers disease (AD), yet underlying mechanisms remain poorly defined. The NIA-AA classifies AD using amyloid (A), tau (T), and neurodegeneration [(N)] biomarkers. We applied this framework to characterize AT(N) profiles and clinical correlates in epilepsy. MethodsEighty-four older adults with focal epilepsy (mean age=66.3 years) from the Brain Aging and Cognition in Epilepsy (BrACE) study were classified as A+, T+, and/or (N)+ using plasma {beta}-amyloid (A{beta}) 42/40 ratio, phosphorylated tau 181 (p-tau181), and neurofilament light chain (NfL) levels, and grouped into normal, AD-continuum, and non-AD pathologic change. Demographic, clinical, and cognitive characteristics were compared. Cognition was assessed using the International Classification of Cognitive Disorders in Epilepsy (IC-CoDE) and the Montreal Cognitive Assessment (MoCA). Memory was examined using IC-CoDE memory domain classification, with word-list delayed recall analyzed separately. Associations with cognition were modeled using logistic and linear regression. Secondary analyses examined biomarkers continuously, including p-tau217, and substituted hippocampal volume for NfL. ResultsOnly 32% of participants had normal biomarkers, while 37% were on the AD-continuum and 31% showed non-AD pathologic change. Participants with normal biomarkers were younger with shorter epilepsy duration, whereas APOE-{varepsilon}4 carriers were enriched in the AD-continuum group. Early-onset compared to late-onset epilepsy (cutoff:[&ge;]55 years) showed higher odds of biomarker abnormality (aOR=8.84, 95% CI [2.35, 41.89], P=0.003), driven by elevated p-tau217, NfL, and greater amyloid burden. While categorical AT(N) profiles were not associated with cognition, higher p-tau181 levels were independently associated with lower word-list delayed recall (95% CI [-10.31, -0.86], P=0.021). Substituting hippocampal volume for NfL shifted more participants to normal profiles (48% vs. 32%) and fewer to non-AD pathologic change (15% vs. 31%). DiscussionAT(N) biomarker profiles showed substantial heterogeneity, with higher abnormality rates than in aging populations, particularly among those with early-onset epilepsy. Continuous p-tau181 was associated with memory performance while categorical AT(N) profiles were not, and NfL and hippocampal volume showed discordant classifications, highlighting divergence across neurodegeneration markers. These findings underscore the complexity of applying AD-centric frameworks to epilepsy and support multimodal, epilepsy-adapted biomarker approaches to characterize neurodegenerative risk.

BackgroundParkinsons disease (PD) genetics research has predominantly focused on populations of European ancestry, limiting understanding of disease mechanisms across diverse populations. African-Caribbean communities harbor complex genetic admixture and exhibit distinct clinical features, yet remain underrepresented in PD genetic studies. We investigated ancestry-specific molecular signatures underlying PD using rare variant burden analysis in geographically and genetically distinct cohorts. MethodsUsing a discovery cohort design and gene-based rare-variant aggregation testing, we performed RNA-sequencing on peripheral blood mononuclear cells from 33 participants: Montreal, Canada (n=16; 8 PD, 8 controls) and Guadeloupe, French West Indies (n=17; 9 PD, 8 controls). We conducted gene-based rare variant burden testing, protein-protein interaction network analysis, pathway enrichment, and linkage disequilibrium (LD) profiling. Clinical assessments included MDS-UPDRS, Hoehn & Yahr staging, and evaluation of prodromal and autonomic features. ResultsPrincipal component analysis revealed distinct population structure, with Montreal participants forming a homogeneous cluster and Guadeloupe participants displaying greater variance consistent with African-European admixture. Ancestry-stratified burden analysis identified divergent immune pathway enrichments: IL-17 signaling predominated in PD patients from Montreal (FDR=0.04), while MHC class II antigen presentation and interferon-{gamma} pathways characterized PD patients from Guadeloupe (FDR=1.59x10-). A NOD2 frameshift variant (rs2066847) was identified in 3/8 Montreal patients, providing a mechanistic link to IL-17 pathway dysregulation. LD analysis revealed ancestry-specific haplotype structures, with 14 African-admixed American-specific LD pairs exclusive to Guadeloupe participants and 11 European-specific pairs present in both populations, demonstrating distinct haplotype architectures shaped by ancestry. Clinical differences aligned with molecular findings: Montreal patients showed higher prevalence of REM sleep behavior disorder (71.4% vs 37.5%) and hyposmia (54.3% vs 22.5%), while Guadeloupe patients showed more autonomic symptoms. Control-only comparison showed no pathway enrichments, validating that PD findings reflect disease-associated mechanisms rather than population stratification. ConclusionsTogether, these findings provide evidence for ancestry-specific immune signatures in PD, challenging a one-size-fits-all paradigm in neurodegenerative disease genetics. The identification of distinct molecular pathways underlying clinically overlapping phenotypes suggests PD may encompass multiple molecular entities converging on shared symptoms. These findings emphasize the necessity of ancestry-inclusive research for advancing mechanistic understanding and achieving equity in precision medicine for neurodegenerative disorders.

Background and Objectives: Older adults with epilepsy are at increased risk for Alzheimer's disease (AD), yet the mechanisms underlying this association remain poorly understood. We applied a validated AD neuroimaging signature to older adults with epilepsy to examine 1) whether older adults with epilepsy mirror AD-related changes, 2) associations with clinical, cognitive, and plasma biomarker outcomes, and 3) utility for identifying subgroups at heightened risk for cognitive decline. Our multicenter, prospectively enrolled cohort allowed for direct examination of differences in AD signatures between those with early-onset and late-onset unexplained epilepsy. Methods: Participants included 449 older adults: 87 with focal epilepsy from the multicenter Brain Aging and Cognition in Epilepsy (BrACE) cohort (age=66.10 [SD=6.86], including early-onset (<55 years at seizure onset) and late-onset ([&ge;]55 years at seizure onset) epilepsy); 362 from the Alzheimer's Disease Neuroimaging Initiative (ADNI), including cognitively unimpaired (CU) healthy controls and individuals with mild cognitive impairment (MCI) or AD dementia. An AD signature was derived from regional cortical thickness and hippocampal volume weighted by their sensitivity to AD-related neurodegeneration in prior work. Associations between the AD signature, epilepsy characteristics, plasma biomarkers ({beta}-amyloid 42/40, phosphorylated tau [pTau217, pTau181], neurofilament light chain [NfL]), and cognition were evaluated in BrACE. Results: Participants with epilepsy demonstrated more AD-like signatures compared to ADNI CU controls ({beta}= -0.43, p<0.001), reflecting reduced thickness/volume in AD-vulnerable regions. This effect was stronger among early-onset ({beta}= -0.57) versus late-onset ({beta}= -0.26) epilepsy. In BrACE, the AD signature correlated with NfL ({beta}= -0.30, p=0.050), memory performance ({beta}= 0.30, p=0.006), and predicted greater odds of cognitive impairment specifically among those with early-onset, but not late-onset, epilepsy (interaction p=0.043). Further, among those with early-onset epilepsy, the AD signature significantly improved identification of cognitive impairment over and beyond the effects of plasma AD biomarkers (p=0.041). Findings were similar when examining the effects of epilepsy duration rather than epilepsy onset age. Discussion: AD neuroimaging signatures may help identify clinically meaningful subgroups among older adults with epilepsy, particularly when integrated with AD biomarkers. Findings support a multimodal framework for assessing AD-related risk in epilepsy and highlight interactive effects of epilepsy chronicity and AD-related processes that can influence cognitive outcomes.

ObjectiveLevetiracetam is commonly prescribed for seizure prophylaxis after acute ischemic stroke (AIS) and often continued beyond discharge. While its short-term effectiveness for preventing post-stroke seizures is established, it is unclear whether prolonged use improves survival, particularly in older adults. We estimated the effect of continued levetiracetam use on 90-day mortality among Medicare beneficiaries after AIS. MethodsUsing Traditional Medicare claims data (2008-2021), we identified beneficiaries aged [&ge;]66 years hospitalized for AIS who initiated outpatient levetiracetam within 90 days of discharge. After one month of continued post-stroke use of levetiracetam (start of follow-up), we compared 90-day mortality between patients with a new levetiracetam dispensation within a 14-day grace period post-follow up and those without one. We performed cloning, censoring and weighting to address immortal time bias and estimated standardized mortality risks, risk differences, and 95% confidence intervals (CI). ResultsAmong 3,212 eligible beneficiaries, 1,779 (55.4%) received a new levetiracetam dispensation within the 14-day grace period. Median age was 76 years (IQR 70-83); 57.8% were female. After adjustment for demographics, hospitalization characteristics, timing of initiation, and comorbidities, continued use was associated with lower 90-day mortality than discontinuation (53 vs 62 deaths per 1,000; risk difference -9 per 1,000; 95% CI: (-12,-5)). The reduction was observed primarily among patients aged [&ge;]75 years. SignificanceAmong older Medicare beneficiaries who initiated levetiracetam after AIS, continued outpatient use was associated with modestly lower 90-day mortality, particularly in those aged [&ge;]75 years. These findings suggest potential benefits of levetiracetam continuation beyond the immediate post-stroke period.

BackgroundSleep-wake and circadian disturbances are increasingly recognised in people living with amyotrophic lateral sclerosis (plwALS), but endogenous circadian phase timing and its prognostic significance in early disease remain unclear. We assessed whether salivary dim-light melatonin onset (DLMO), an objective marker of central circadian phase, is altered in early plwALS and whether it provides prognostic information. MethodsIn this prospective longitudinal observational study, plwALS within 18 months of symptom onset underwent home-based salivary melatonin sampling under dim-light conditions at six predefined time points around habitual sleep onset (HSO). Melatonin profiles were modeled using cubic smoothing splines, and DLMO was defined as the first time the fitted curve reached 3 pg/mL. Clinical, respiratory, and sleep assessments were collected at baseline (T0) and after 6 months (T6); a subgroup repeated saliva sampling at T6. Age- and sex-matched controls underwent melatonin profiling. Associations with disease progression, incident respiratory symptoms, and survival/tracheostomy were examined using regressions and survival analyses. ResultsFifty plwALS were enrolled. Compared with controls, plwALS showed an earlier DLMO (20:24{+/-}1:18 vs 20:58{+/-}0:50; p=0.028) despite similar HSO and chronotype. Within ALS cohort, a later baseline DLMO correlated with worse functional/motor status, faster progression of disease, incident dyspnea/orthopnea by T6 (adjusted OR 3.02; p=0.017), and poorer survival/tracheostomy-free outcome. In re-sampled subgroup (n=28), DLMO and other melatonin-derived metrics did not change over [~]6 months. ConclusionsCircadian phase alterations are detectable in early-ALS. Baseline DLMO may represent a non-invasive prognostic biomarker for progression, respiratory symptom emergence and survival, warranting validation in larger multicentre cohorts. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSSleep and circadian disturbances are increasingly recognised as early, biologically relevant non-motor features of amyotrophic lateral sclerosis (ALS), and recent translational and neuroimaging studies support early involvement of sleep-regulatory and hypothalamic networks. Dim-light melatonin onset (DLMO) is an established objective marker of central circadian phase, but endogenous melatonin timing in ALS and its prognostic relevance have not been previously defined. What this study addsIn a prospective cohort of patients with early-ALS, salivary DLMO was altered relative to matched controls, and within the ALS cohort a later baseline DLMO was associated with worse functional and motor status, faster subsequent progression, incident respiratory symptoms at 6 months, and poorer survival/tracheostomy-free outcome. These findings identify circadian phase timing as a clinically informative signal in early-ALS. How this study might affect research, practice or policyIf validated, DLMO could complement established prognostic tools in early-ALS and support enrichment of phase-aware clinical trials. They also provide a rationale for phase-aware longitudinal studies integrating circadian phenotyping, respiratory, imaging, and plasmatic biomarker and for testing whether interventions targeting circadian alignment can improve symptoms or clinical trajectories in selected patients with ALS.

ObjectiveAccumulation of hyperphosphorylated tau (pTau) is a proposed mechanism for demen{-}tia associated with epileptic seizures but the evidence directly linking seizures and pTau accumula{-}tion remains weak. Here, we aimed at determining the burden of pTau pathology in a historical co{-}hort of epilepsy patients who developed dementia hypothesizing an association between seizure onset zone and pTau accumulation. MethodsPost-mortem brain tissue was obtained from the Danish Brain Collection comprising autopsies from psychiatric patients that died between 1945-1982. Sections from the middle frontal gyrus, thalamus, and medial temporal lobe from both hemispheres were stained for pTau and beta-amyloid and quantified by a blinded assessor. Comparisons were conducted using non-parametric tests. ResultsThirty-two patients (median age 61.5 years, 59.4% men) were included. pTau pathology was detected in 22 brains (68.8%), with Tau Burden Scores (0-108) ranging from 2 (almost unde-tectable) to 94 (high load; median 6.5). pTau burden was significantly associated with age at death (Spearmans rho = 0.62, p < 0.001) and duration of epilepsy (Spearmans rho = 0.47, p = 0.02), but not with other clinical variables. Among 11 patients with focal seizures, a significantly higher pTau (p = 0.02) but not a higher beta-amyloid burden (p = 1.0) was observed in the epileptogenic hemi{-}sphere. 81.3% of all patients (n=26) had a competing dementia diagnosis: three patients fulfilled the pathological criteria of Alzheimers dementia, 13 patients had clinical and/or autoptic diagnosis of vascular dementia. SignificanceIn this cohort, dementia epileptica was associated with increased pTau burden in the epileptogenic hemisphere and time since diagnosis supporting the concept of seizure-induced pTau accumulation. However, pTau is unlikely to be the primary neuropathological link between epilepsy and dementia in the cohort studied given the overall mild pathology and competing diagnoses.

BackgroundEpidemiological studies show an inverse association between cigarette smoking and Parkinsons disease (PD), suggesting a potential protective effect of smoking on PD incidence, despite the well-established and overwhelming harms of smoking to human health. We integrated genomic and proteomic approaches to investigate the causality and molecular basis of this potential relationship. MethodsWe analyzed summary statistics from genome-wide association studies (GWAS) of smoking initiation (SmkInit), smoking intensity, and PD. Two-sample Mendelian randomization (MR) tested whether genetic liability to smoking behaviors causally influences PD risk. Shared genomic architecture was quantified using MiXeR, and conjunctional false discovery rate (conjFDR) analysis identified loci jointly associated with smoking and PD, which were then mapped to genes and tested for tissue enrichment. To identify mediating proteins, we integrated dorsolateral prefrontal cortex proteomic data with GWAS using proteome-wide association studies (PWAS), summary-based MR, heterogeneity in dependent instruments testing, and colocalization. Finally, the druggability of convergent genes was evaluated. ResultsMR analyses indicated a protective effect of genetic liability to SmkInit on PD risk (OR = 0.78, 95% CI: 0.67-0.91, P = 1.5 x 10-3), which was consistent across sensitivity analyses and not suggestive of directional pleiotropy. However, no significant effect of genetic liability to cigarettes per day (CigDay) on PD risk was found. MiXeR revealed modest polygenic overlap between SmkInit and PD (13.9%; genetic correlation rg = -0.16) and between CigDay and PD (22.9%; rg = -0.09). ConjFDR identified 95 shared loci for SmkInit-PD and 26 for CigDay-PD. SmkInit-PD loci mapped to genes involved in neurotrophic signaling, synaptic organization, microglial modulation, and mitochondrial stress responses, with expression enriched in substantia nigra, basal ganglia, and interconnected cortical regions. PWAS identified 11 proteins shared by PD and SmkInit and 5 shared with CigDay, several of which (AKT3, MAPT, RIT2, EXD2, and PPP3CC) were supported by both genomic and proteomic analyses. Druggability assessment highlighted six proteins with existing pharmacologic modulation potential, spanning neurotrophic, microglial, proteostatic, and ion-channel pathways. ConclusionsGenetic liability to smoking initiation appears to confer modest protection against PD. Integrative genomic and proteomic evidence converges on neurotrophic, synaptic, microglial, and mitochondrial pathways as shared mechanisms, identifying biologically coherent potential therapeutic targets for advancing smoke-free neuroprotective strategies in PD.

Objective Memory impairment is a frequent comorbidity of focal epilepsy, incompletely explained by seizure frequency or structural pathology. Ictal and postictal hippocampal dysfunction disrupt memory processes, but their cumulative impact remains poorly quantified. This study introduces cumulative hippocampal seizure-related burden metrics and examines their association with long-term memory consolidation. Methods Twenty consecutive patients undergoing stereo-EEG in Marseille (2016-2018) were prospectively included. Continuous stereo-EEG recordings between two memory assessments (30 minutes and one week post-encoding) were analysed. Hippocampal ictal involvement and durations were assessed using epileptogenicity markers and visual stereo-EEG analysis. The postictal period was quantified using permutation entropy. Cumulative hippocampal seizure-related burden metrics (ictal, postictal and combined: c-HipSZB) were computed across hippocampus-involving ictal events. Verbal and visual memory were assessed using standardized recall and recognition tasks. Associations were examined using univariate and multivariate analyses. Results Higher dominant-hemisphere hippocampal burden was associated with poorer one-week verbal memory (performance and retention), independently of most covariates. Higher c-HipSZB was associated with lower total recall performance (RT; free + cued) and RT retention ({beta} = -25.04 and -23.88; R2 = 0.57 and 0.53; p < 0.05) and accounted for the greatest variance in both outcomes (adjusted R2= 0.59 and 0.53; {beta} = -25.45 and -24.27; p < 0.01), particularly when adjusting for epilepsy duration. No robust associations were observed between non-dominant-hemisphere hippocampal seizure-related burden metrics and visual memory. Effects predominantly involved recall. Interpretation Cumulative ictal-postictal hippocampal dysfunction is a major determinant of impaired long-term verbal memory consolidation in focal epilepsy.

Focal cortical dysplasias (FCDs) are one of the most common structural causes of drug-resistant epilepsy in children but are frequently subtle and difficult to detect on conventional MRI. Many automated lesion detection methods have therefore been proposed to support neuroradiological assessment. In this study, we externally validated two recently developed deep-learning approaches for FCD detection, MELD Graph and 3D-nnUNet, in a pediatric cohort. In this retrospective single-center study, brain MRI scans of 71 children evaluated for epilepsy were analyzed, including 35 MRI-positive patients with suspected FCD and 36 MRI-negative cases based on the primary radiology reports. Both models were applied to standard 3D T1-weighted and 3D FLAIR images. Detected lesions were reviewed by an experienced pediatric neuroradiologist and classified as true positive, false positive, or false negative. Clinical semiology and EEG findings were additionally evaluated for cases with false-positive detections. At the lesion level, MELD Graph achieved a precision of 0.85 and recall of 0.52, while 3D-nnUNet achieved a precision of 0.91 and recall of 0.48. In the MRI-negative patients, MELD Graph produced more false-positive detections than 3D-nnUNet (0.53 vs. 0.14 false-positive lesions per patient). At the patient level, MELD Graph showed slightly higher sensitivity than 3D-nnUNet (0.63 vs. 0.54), whereas 3D-nnUNet demonstrated markedly higher specificity (0.86 vs. 0.56). Improved FLAIR image quality was associated with trends toward improved model performance. Both models demonstrated high precision but moderate sensitivity, indicating that they are valuable decision-support tools but cannot replace expert neuroradiological evaluation. Optimized MRI acquisition protocols are needed to further improve automated lesion detection in pediatric epilepsy.

BackgroundAmyotrophic lateral sclerosis (ALS) is characterized by profound metabolic reprogramming, yet the lack of biomarkers for specific druggable targets remains a major hurdle for precision medicine. We hypothesized that peripheral lipid biosynthetic signatures could serve as both prognostic indicators and a roadmap for identifying novel disease-modifying targets. MethodsWe assessed serum fatty acid (FA) metabolic pathways in two independent longitudinal cohorts (n = 37 and n = 38) using high-dimensional CoxBoost modeling. Primary outcomes were survival and functional staging milestones, including non-invasive ventilation and gastrostomy. The biological relevance of the identified candidate was further assessed through correlation with plasma neurofilament light-chain (NfL) levels. Causality and therapeutic potential were validated in Drosophila melanogaster models of TDP-43 proteinopathy via genetic ablation and pharmacological inhibition. ResultsOur multi-parametric model, comprising two clinical variables and the estimated ELOVL6 (elongation of very long-chain fatty acids protein 6) activity, demonstrated robust prognostic accuracy (Unos C 0.69) across both cohorts; ELOVL6 activity served as a strong independent predictor of mortality and functional decline. Notably, high ELOVL6 activity significantly correlated with elevated plasma NfL levels (p < 0.01), linking peripheral elongation imbalances to central axonal damage. In Drosophila, ELOVL6 overactivation was identified as a conserved pathological consequence of TDP-43 dysfunction, characterized by an increased C18:0/C16:0 ratio in both loss-of-function and gain-of-function models. Inhibition of ELOVL6, either genetically or pharmacologically, rescued neuromuscular junction integrity, prolonged survival, and significantly reduced pathological TDP-43 phosphorylation in glial models. ConclusionThese findings position ELOVL6 as a promising modifiable metabolic node with potential for disease-modifying intervention in ALS. Beyond its potential utility for identifying high-risk metabolic profiles and assisting in prognostic counseling, ELOVL6 bridges systemic lipid dysregulation with TDP-43 proteinopathy. Targeting this pathway offers a dual opportunity: as a biological marker to supplement clinical staging and as a druggable enzymatic target to ameliorate motor neuron degeneration. HIGHLIGHTSO_LISystemic ELOVL6 activity is a robust independent predictor of ALS survival. C_LIO_LIHigh ELOVL6 levels correlate with plasma NfL and functional decline. C_LIO_LIInhibition of ELOVL6 rescues NMJ integrity and survival in Drosophila models. C_LIO_LIPharmacological targeting of ELOVL6 reduces glial TDP-43 phosphorylation. C_LIO_LIELOVL6 represents a druggable metabolic node linking lipids to proteinopathy. C_LI

BackgroundAccurate diagnosis of multiple system atrophy (MSA) is critical for clinical management and efficient trial designs, yet remains challenging, particularly distinguishing MSA (especially cerebellar-subtype [MSA-C]) from sporadic adult-onset ataxia (SAOA). Combining a marker of neuroaxonal degeneration, neurofilament light chain (NfL), with a marker of the pathogenic MSA hallmark, -synuclein seeding activity, may define a mechanistically-informed CSF signature of MSA, enabling sensitive and specific differentiation from SAOA even in early disease. MethodsWe analyzed 60 cross-sectional patient CSF samples (n=32 clinically diagnosed MSA [MSAclin] 22/32 MSA-C; n=28 SAOA) for NfL (Simoa) and -synuclein seeding activity (seed amplification assay [synSAA], Piperazine-N,N-bis(2-ethanesulfonic acid)-based), and assessed diagnostic accuracy, disease-duration correlations, and trial power using biomarker-based stratification. ResultsAge-adjusted NfL was higher in MSAclin than SAOA (3859 vs. 997pg/mL), yielding 96.9% sensitivity and 85.7% specificity. SynSAA was concordant with clinical diagnosis (25/32 MSAclin synSAA-positive; 23/28 SAOA synSAA-negative), with 78.1% sensitivity and 85.2% specificity (all confirmed in MSA-C subgroup). Both biomarkers displayed divergent trajectories with disease duration: NfL peaked early before declining (r=-0.45, p=0.01); whereas synSAA maximum fluorescence intensity increased (r=0.42, p=0.016), suggesting greater synSAA signal with accumulating MSA burden. Integrating both biomarkers in MSA treatment trials allows sample-size reduction by 20% versus NfL alone. ConclusionsCSF NfL and synSAA capture complementary aspects of MSA biology: while NfL provides high diagnostic accuracy for MSAclin, peaking early, synSAA adds mechanistic specificity for -synuclein seeding activity and might allow target engagement assessment. Combined, they might enable biological diagnostic frameworks, molecular trial stratification, and treatment monitoring in MSA. Key messagesO_ST_ABSWhat is already known on this topicC_ST_ABSWhile highly warranted for clinical management and efficient treatment trial design, accurate diagnosis of multiple system atrophy (MSA) against overlapping and reciprocally mimicking conditions such as sporadic adult-onset ataxia (SAOA) remains clinically challenging, especially in early disease stages. A mechanistically informed biofluid signature of MSA might enable sensitive and specific differentiation from SAOA, even in early disease stage. Recently merging molecular markers reflecting neuroaxonal damage (NfL) and -synuclein seeding activity (measured by the seed amplification assay; synSAA) might here show particular promise. What this study addsThis is the first study to systematically assess the ability of both CSF NfL and CSF -synuclein seeding activity to distinguish clinically diagnosed MSA (MSAclin) from SAOA, thereby offering a window into underlying MSA biology in patients in vivo. Our findings suggest that the rate of axonal degeneration is most pronounced in early MSA disease stages but decreases with longer disease duration; whereas -synuclein seeding signal activity increases as MSA-related disease burden accumulates. Finally, it demonstrates the impact of a combined molecular fluid signature of MSA for improving trial design: a biomarker-based stratification of MSA subjects in future MSA treatment trials combining NfL plus -synuclein seeding activity allows to reduce sample sizes by 20% compared to NfL alone. How this study might affect research, practice or policyThe findings from this study may help to molecularly diagnose patients with MSA against overlapping and reciprocally mimicking conditions such as SAOA, in particular and even in early disease stages. Moreover, they might lay the foundation for a future biologically-informed diagnostic framework of MSA; support trial stratification for more efficient upcoming MSA treatment trials; and might facilitate molecular treatment effect monitoring in MSA, in particular in synuclein-targeted treatment trials.

ImportanceAccurate diagnosis of neurodegenerative movement disorders is challenging because of a lack of in vivo biomarkers, overlapping clinical features and a delay in the emergence of pathognomonic features. ObjectiveTo evaluate clinicopathological correlation, diagnostic accuracy, genetic association with pathology, and ancestry-related differences in a multi-ancestry brain bank cohort. DesignMulticentre retrospective autopsy cohort study on donors enrolled between 1985 - 2024. Setting11 academic brain banks in the UK, US and Australia ParticipantsBrain donors identified from participating brain banks with available brain tissue and a clinical diagnosis of Parkinsons disease, Parkinsons disease dementia, dementia with Lewy bodies, progressive supranuclear palsy, corticobasal syndrome, multiple system atrophy, or neurologically normal controls. ExposureGenetic variant carrier status and clinical diagnostic category. Main outcomeClinical diagnostic accuracy; Lewy body and Alzheimers disease pathology burden; survival; association with genetic variants and genetically inferred ancestry. ResultsWe studied 3,353 brain donors (1281 [38.2%] female, mean [SD] age at death, 76.8 [10.6] years). Misdiagnosis rates for movement disorders ranged approximately from 10% - 20%. Clinical diagnoses of dementia with parkinsonism (PDD/DLB) were more strongly associated with Lewy body pathology than Parkinsons disease without dementia (OR = 1{middle dot}96, 95% CI = 1{middle dot}30 - 3{middle dot}04, p = 7{middle dot}2e-04). Lewy pathology was identified in 4% of neurologically normal controls. Alzheimers disease co-pathology was present in 40% of cases with Lewy body disease. GBA1 variant carriers exhibited greater Lewy body burden compared with noncarriers (OR = 1{middle dot}94, 95% CI = 1{middle dot}24 - 3{middle dot}03, p = 0{middle dot}01) or LRRK2 carriers (OR = 7{middle dot}44, 95% CI = 2{middle dot}16 - 25{middle dot}64, p = 0{middle dot}01). Pathological diagnoses differed by ancestry, with South Asian donors more likely to have progressive supranuclear palsy pathology and Ashkenazi Jewish donors more likely to have Lewy body disease (p < 0.0001), independent of GBA1 and LRRK2 mutation status. Conclusion and RelevanceOur findings highlight the value of integrating genetic and pathological data to improve diagnostic accuracy. The high prevalence of Alzheimers disease co-pathology and ancestry-related differences in pathology point to the need for biologically informed diagnostic tools. These results support the integration of genetically and pathologically stratified approaches, correlating pathology with in vivo biomarkers, for future therapeutic trials. FundingMedical Research Council, Global Parkinsons Genetic Program/Aligning Science Across Parkinsons Key PointsO_ST_ABSQuestionC_ST_ABSHow do genetic variants and neuropathology influence clinical features and diagnostic accuracy in movement disorders? FindingsIn this multi-ancestry brain bank series including over 3000 individuals, clinical misdiagnosis was common. Dementia with parkinsonism was more strongly associated with Lewy body (LB) pathology than Parkinsons disease without dementia, and Alzheimers disease co-pathology was frequent. Genetic variation was associated with pathological differences. GBA1 carriers had greater LB burden, while LRRK2 pathogenic variant carriers had a lower LB burden and longer survival. Pathological diagnosis differed by ancestry. MeaningIntegrating genetics and neuropathology may improve diagnosis and support pathology-informed therapeutic trials.

Background: Progressive multiple sclerosis (MS) is characterized by ongoing neurodegeneration and limited therapeutic options. Circulating metabolites provide insight into disease biology, yet biomarkers that predict disability progression and reflect treatment response are lacking. We aimed to identify metabolomic signatures associated with longitudinal MRI measures of brain atrophy and to evaluate whether ibudilast treatment was associated with metabolite trajectories over time. Methods: We repeatedly profiled 1,726 plasma metabolites using untargeted UPLC-MS/MS in 244 participants from the 96-week SPRINT-MS randomized trial of oral ibudilast, up to 100 mg daily, versus placebo. Weighted gene co-expression network analysis was used to derive groups of related metabolites. Associations between baseline metabolite groups and longitudinal MRI outcomes were evaluated using linear mixed-effects models adjusted for demographic, clinical, and treatment covariates. The primary outcome was the rate of whole-brain atrophy measured by brain parenchymal fraction (BPF), defined as the proportion of intracranial volume occupied by brain tissue. Secondary outcomes included white matter fraction (WMF), gray matter fraction (GMF), and cortical thickness (CTH). Metabolite groups nominally associated with MRI outcomes, defined as p < 0.05, were followed by individual metabolite analyses to identify potential drivers. Significant metabolites were tested for replication in a comparable real-world observational HEAL-MS cohort with longitudinal MRI data. Lastly, we tested whether ibudilast treatment was associated with metabolite trajectories and performed metabolite set enrichment analysis. Findings: Higher baseline levels of glycerophospholipids were associated with slower decline in both BPF and WMF, and sphingomyelins were similarly associated with slower BPF decline. For example, higher 1-palmityl-2-stearoyl-GPC (O-16:0/18:0) levels were associated with slower BPF decline in SPRINT-MS (beta = 0.016 [95% CI: 0.008, 0.024]; p = 4.35 x 10^-5) and replicated in HEAL-MS (beta = 0.108 [95% CI: 0.006, 0.211]; p = 3.90 x 10^-2). Metabolites associated with GMF preservation were enriched in androgenic steroids and steroid sulfates, with consistent positive associations observed in the replication cohort, whereas metabolites inversely associated with CTH were predominantly xenobiotic-related. Ibudilast treatment was associated with increased sphingomyelin species, such as palmitoyl sphingomyelin (d18:1/16:0; beta = 0.185 [95% CI: 0.085, 0.286]; FDR = 1.79 x 10^-2), and decreased levels of amino acid-related metabolites, such as anthranilate (beta = -0.270 [95% CI: -0.403, -0.137]; FDR = 3.87 x 10^-2). Pathway-based analyses corroborated these findings, highlighting glycerophospholipid and sphingolipid metabolism as key pathways implicated in brain atrophy in MS. Interpretation: Distinct lipid subsets were associated with slower brain atrophy in people with MS, and ibudilast treatment was associated with metabolite alterations in potentially neuroprotective directions. Metabolomics may provide prognostic and pharmacodynamic biomarkers for progressive MS.

ObjectiveSpinocerebellar ataxia type 1 (SCA1) is a rare, inherited neurodegenerative disease characterised by progressive deterioration of motor and cognitive function. Here, we illustrate the pattern and evolution of brain atrophy in people with SCA1 using a large multisite dataset. MethodsStructural magnetic resonance imaging data from SCA1 (n=152) and healthy control (n=131) participants from seven sites and two consortia were analyzed using voxel-based morphometry. Cross-sectional stratification and correlations were undertaken with ataxia severity and duration to profile disease evolution. Cerebrocerebellar structural covariance analysis was used to understand the relationship between cerebral and cerebellar tissue atrophy. ResultsAtrophy in SCA1 first manifests in the lower brainstem and cerebellar white matter (WM), before progressing to the pons, anterior cerebellum, and cerebellar lobule IX. The midbrain and peri-thalamic WM and the remainder of the cerebellar cortex are then affected, with preferential involvement of specific motor and cognitive areas. Finally, degeneration in the striatum and cerebral WM corresponding to the corticospinal tract become apparent. Atrophy and correlations with ataxia severity are most pronounced in the cerebellar WM and pons. Structural covariance analysis showed reduced correlations between cerebellar and cerebral WM volume in SCA1 participants. InterpretationCross-sectional stratification of a large SCA1 cohort by ataxia severity indicates a pattern of atrophy spread across the brainstem, cerebellum, and subcortical grey and white matter. Ongoing volume loss throughout the disease course is most evident in a core set of infra-tentorial brain regions. Atrophy of cerebellum spans both motor and cognitive functional zones. Cerebellar degeneration is not directly mirrored by downstream effects in the cerebrum.